Not able to import json from commandline for Python

Question

I am currently tring to work with import a json input that is accepted by Python through a commandline argument and I am trying to save the different values to JSON to a list. I am having issues with my code given below and have attached both the code and the error I get below. Any help much appreciated.

import sys
import json
def lookup1 ():
    jsonData = json.loads(sys.argv[1])
    print jsonData
    jsonList = [jsonData['proxy'],jsonData['OS']]
    print jsonList

lookup1()

The error is given below:

$ python dynamicMapper.py '{'proxy':1,'OS':2}'
Traceback (most recent call last):
  File "dynamicMapper.py", line 9, in <module>
    lookup1()
  File "dynamicMapper.py", line 4, in lookup1
    jsonData = json.loads(sys.argv[1])
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 382, in raw_decode
    obj, end = self.scan_once(s, idx)
ValueError: Expecting property name: line 1 column 2 (char 1)

The commadline argunet that I give is python dynamicMapper.py '{'proxy':1,'OS':2}' I am not able to find out what is causing this error and if my approach is right.

niemmi · Accepted Answer · 2016-11-25 07:33:16Z

2

The script is working fine, you just need to call it the right way:

python dynamicMapper.py '{"proxy":1,"OS":2}'
{u'OS': 2, u'proxy': 1}
[1, 2]

In JSON the strings are quoted with double quotes instead of single quotes. You also need to quote the string passed to script so that shell understands it being a single argument.

edited Nov 25, 2016 at 7:33

answered Nov 25, 2016 at 6:01

niemmi

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2 Comments

lordlabakdas Over a year ago

ah, thanks! I guess what was wrong was the way I called it. I was using python dynamicMapper.py {'proxy':1,'OS':2}. I though single and double quotes were interchangeable. Probably not in a dict, Is that right?

niemmi Over a year ago

@lordlabakdas You're not passing a dict to to the script but a string containing JSON that your script then parses with json.loads.

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